The present invention pertains to numerically controlled/computer-operated manufacturing machines that manipulate one or more tools to perform manufacturing tasks and, more particularly, to the accuracy of such manufacturing machines.
Numerically controlled/computer-operated manufacturing machines that manipulate tools to perform manufacturing tasks, such as machining parts, are widely used. It is important for the accuracy of mechanical movements of manufacturing machines to be maintained in order for the machines to accurately manufacture parts. Accordingly, it is common to periodically remove manufacturing machines from service in order to fully check their accuracy and perform any adjustments that are necessary. The accuracy of manufacturing machines is typically checked with traditional metrological devices, which include laser transmitters and receivers, ball-bar testing equipment, and the like. It is common for a manufacturing machine to be out of service for several days in order for its accuracy to be fully checked.
Removing manufacturing machines from service in order to check their accuracy detrimentally decreases the number of parts that the manufacturing machines fabricate. Accordingly, it is common for manufacturing machines to be operated for as long as possible before being removed from service for accuracy checks. This can disadvantageously result in the manufacture of marginally acceptable or unacceptable parts.
It is common for parts manufactured by a manufacturing machine to be inspected after they are removed from the manufacturing machine, and this inspection is often referred to as a post operation inspection. Post operation inspections can be disadvantageously time consuming and/or require expensive equipment. For example, post operation inspections can be facilitated through the use of hand-operated calipers, micrometers, coordinate measuring machines, laser devices and other conventional inspection tools.
It is common for a problem with a manufacturing machine to be initially identified via post operation inspections due to the disincentive for frequently removing a manufacturing machine from service for a full accuracy check. However, post operation inspections often do not identify specific corrective actions that need to be taken for a manufacturing machine that has produced an unacceptable part. The act of measuring a part is a way of identifying if there is a discrepancy, but the data associated with the measurement of the part often is not very useful at identifying why the discrepancy occurred. In addition, clamping, lifting, and transporting actions that are typically associated with moving manufactured parts from a manufacturing machine to an inspection station or machine, as well as differences in temperature between the manufacturing location and the inspection location, can disadvantageously increase the number of variables that can have an impact on the post operation inspection process.
In summary, it can be disadvantageous to remove a manufacturing machine from service for the extended period of time that is required to perform a full accuracy check for the manufacturing machine. It can also be disadvantageous to leave a manufacturing machine in service for too long and have it fabricate marginally acceptable or unacceptable parts. Further, post operation inspection procedures can be disadvantageously time consuming and/or expensive, they may not provide much useful information about which aspect of the manufacturing machine is not operating accurately, and they may introduce complicating variables into any associated analysis of the manufacturing machine.
The present invention solves the above and other problems by providing a certifying system that is capable of being associated with and operated in conjunction with a manufacturing machine. The certifying system can decrease the number of full accuracy checks that are performed for the manufacturing machine, can identify when the manufacturing machine should be subjected to a full accuracy check, and can provide current information about the accuracy of the manufacturing machine between full accuracy checks, so that the manufacturing machine may be utilized to accurately inspect parts manufactured thereby in a manner that can reduce the dependence upon post operation inspection.
More specifically, in accordance with one aspect of the present invention, the combined manufacturing machine and certifying system performs operations that carry out a method. The method includes performing a first operation of the manufacturing machine, obtaining first data by quantifying the first operation of the manufacturing machine using first measurement equipment of known accuracy, performing a second operation of the manufacturing machine, obtaining second data by quantifying the second operation of the manufacturing machine using second measurement equipment (e.g., machine-dedicated measurement equipment), determining the accuracy of the second measurement equipment by quantifying the difference between the first and second data, machining a workpiece with the manufacturing machine after determining the accuracy of the second accuracy measurement equipment, performing a third operation of the machine after machining the workpiece, and obtaining third data by quantifying the third operation of the manufacturing machine using the second measurement equipment.
In accordance with another aspect of the present invention, the second and third data are compared in an effort to identify any degradation of the manufacturing equipment.
In accordance with another aspect, the third operation includes operating the manufacturing machine to inspect the workpiece after the workpiece has been machined.
In accordance with another aspect of the present invention, the manufacturing machine and certifying system are combined to provide an improved manufacturing machine that is capable of sequentially machining workpieces by moving tools relative to the workpieces. The improved manufacturing machine includes a holder that is capable of holding a workpiece, and at least one manipulator having a clamp that is operable for gripping the tools. The manipulator is operative for moving the clamp so that a tool gripped by the clamp can be used upon the workpiece. The improved manufacturing machine further includes a stimulus device mounted at a fixed position for remaining fixed relative to the holder while the workpieces are machined in the sequential fashion. The stimulus devices can be optical or mechanical. The improved manufacturing machine further includes a sensor assembly that is capable of being gripped by and carried by the clamp while the clamp is moved relative to the holder. The sensor assembly is operative for generating a signal in response to being proximate the stimulus devices or stimulus provided therefrom. The improved manufacturing machine further includes a computer system that includes a receiver, which is operative for receiving signals generated by the sensor assembly, and a memory containing a database. The computer system is operative for controlling the operation of the manipulator. Initially, the clamp holds the sensor assembly and the manipulator moves the sensor assembly to proximate the stimulus device or a stimulus provided therefrom so that the sensor assembly generates a signal and the signal is received by the receiver. Data representative of the signal is stored in the database. Thereafter, the clamp releases the sensor assembly, retrieves the tool, and the manipulator moves the tool into contact with a workpiece that is being held by the holder. The computer system is also operable for generating a signal if the data in the database exceeds a predetermined value.
The present invention is capable of reducing the amount of time that a manufacturing machine is removed from service for full accuracy checks, and is also capable of obtaining and providing information about the accuracy of the manufacturing machine during times in which the manufacturing machine is in service but the clamp(s) of the manufacturing machine are xe2x80x9cidle.xe2x80x9d Numerous advantages are provided by virtue of the present invention being capable of automatically, frequently, and conveniently verifying the accuracy of a manufacturing machine. For example, the manufacturing machine can accurately inspect a part manufactured thereby, which can reduce the need for post operation inspection. In addition, the present invention is capable of identifying accuracy problems with the manufacturing machine before those problems result in the fabrication of unacceptable parts.